The present invention relates generally to devices for the actuation of keys for acoustic and electronic keyboards.
The piano is a stringed keyboard musical instrument which was derived from the harpsichord and the clavichord. Its primary differences from its predecessors is the hammer and lever action which allows the player to modify the intensity of the sound emanating from the piano depending upon the force employed by the person playing the piano.
The modern piano has six major parts: (1) the frame, which is usually made of iron; (2) the sound board, a thin piece of fine grain spruce which is placed under the strings; (3) the strings made of steel wire which increase in length and thickness from the treble to the bass; (4) the action, which is the mechanism required for propelling the hammers against the string; (5) the pedals, one of which actuates a damper allowing the strings to continue to vibrate even after the keys are released, another known as a soft pedal which either throws all the hammers nearer to the strings so that the striking distance is diminished or shifts the hammers a little to one side so that only a single string instead of two or three strings is struck, and, in some pianos, a third or sustaining pedal that keeps raised only those dampers already raised by the keys at the moment the pedal is applied; and finally (6) the case. The piano""s action functions primarily as follows: a key is pressed down, its tail pivots upward, lifting a lever that throws a hammer against the strings for that key""s note. At the same time a damper is raised from the strings, allowing them to vibrate more freely. When the key is even partially released, the damper falls back onto the strings and silences the note. When the key is fully released, all parts of the mechanism return to their original positions.
The player piano is an evolution of the standard piano which includes a system for automatically actuating the piano keys. There are numerous types of apparatuses available for actuating the piano keys.
Credit for the mechanically operated (or player) piano is generally given to Claude Felix Seytre of Leon, France. His patent was issued in 1842 for a playing piano system that used stiff cardboard sheets. An Englishman named Alex Bain improved the patent in 1848 with a roll operated piano. In 1863 the first pneumatically operated piano was patented and achieved commercial success.
Originally, player pianos operated by means of suction which was created by pumping bellows at the bottom of the piano. This in turn caused the keys to go down, the music roll to turn and other various accessories to operate, such as the sustain pedal and hammer rail. When suction is applied to a pneumatic actuator, it collapses and performs a mechanical function such as playing a note, lifting the dampers, or pushing on the hammer rails. To perform an action each pneumatic actuator must have a valve associated with it for turning each actuator on and off. Pneumatically operated player pianos tended to be extremely complicated machines.
More recently, to overcome the problems associated with using paper rolls and pneumatic controls, electronically operated player pianos have been developed. In these, CD-ROMs, cassette tapes and other electronic storage means replace the paper rolls and electromagnetic actuators such as solenoids control key movement. These electromagnetic actuators generally offer greater control over the movement of the keys, which allows for finer control of the sounds emanating from the player piano.
The size of the player piano mechanisms has also been greatly reduced with the use of electromagnetic actuators. In many cases, electromagnetic actuators were substituted directly for the corresponding pneumatic actuators and were placed beneath the rear of the keys to push the keys up. These push type solenoids were first used in the early 1960s and continue to be used today. Locating the actuators under the rear of the key makes installation problematic. Installation requires cutting a slot along the entire lower side of the piano case, thus permanently disfiguring the piano. Another disadvantage is that the solenoids are mounted separately from the key frame and therefore cannot be removed and serviced with the key frame.
One potential improvement was offered in U.S. Pat. No. 4,383,464 to Brennan which issued in 1983. It discloses an electromagnetic device for actuating piano keys. In this invention, electromagnets were located above the key and behind the fulcrum of the key and operated to pull a piece of magnetic material in the rear of the key upwardly. The electromagnets were positioned forward of the structure that holds the hammer mechanism, known as the tower. Also, the electromagnets did not engage the key itself. Rather, they relied on a magnetic field. The patent was never successful in commercial application. The location of the electromagnetic device was problematic in that there is little room between the rear of the key pivot or fulcrum and in front of the tower. The electromagnetic devices used in the ""464 patent had additional problems in that they charged much slower and thereby consumed excess power and were slow to start up. They generated additional heat and consumed far more power than a solenoid or servomechanism. Additionally, the location of the electromagnetic devices in the ""464 patent would be extremely sensitive to any maintenance work which is performed upon the action due to the fact that if the action is removed and worked upon, the alignment of the electromagnetic devices would require adjustment after the action was reinstalled.
Many other approaches to the actuation of the keys of the piano have been attempted, but all suffer from various shortcomings. It is desirable that an actuation system provide a combination of playing power, key control, and quiet operation. It is also desirable that an actuation system be easily installed into an existing piano without requiring extensive modification to the piano. Presently available systems generally fail to meet this combination of requirements. Therefore, there remains a need for improved player systems.
In many player pianos, it is desirable to sense the movement of the piano keys. This allows the player piano to xe2x80x9crecordxe2x80x9d the playing of a user. Key movement sensing may also be beneficial in the control of playback by allowing the player piano to use some type of a feedback control loop.
Currently, player pianos include some type of actuator mechanism that moves individual piano keys, thereby xe2x80x9cplayingxe2x80x9d the piano. Where key movement sensing is desired, an entirely separate system of key movement sensors is added. Currently available key movement sensing systems have several drawbacks. First, they typically require the addition of a piece of metal to each key which may affect the weight of the key and alter the playing characteristics of the piano. Secondly, because the sensing system is entirely separate from the actuation mechanism, additional wiring and installation is required. This also adversely affects the cost of such a system. Therefore, there remains a need for improved key sensing systems.
Non-acoustical keyboard instruments, such as electronic keyboards, typically include a plurality of keys with some type of sensor located so as to sense movement of each key. When a sensor determines that a key has been moved, a sound is electronically created by the instrument. This differs from a piano wherein sound is created by a mechanical system. A drawback to non-acoustical keyboard instruments is that most lack the xe2x80x9cfeelxe2x80x9d associated with traditional acoustic keyboard instruments. That is, there is a certain feel associated with operating the keys on a traditional acoustic keyboard instrument, such as a piano. This feel results from the mechanical design of the string striking mechanism, the weight of the keys, and other factors. Non-acoustical keyboards lack the mechanical structure of a piano and usually have keys which are significantly less massive. Consequently, the keys feel entirely different when operated. Some musicians consider this a drawback as they would prefer that non-acoustical keyboards have a feel similar to acoustical keyboards such as a piano.
Another drawback to non-acoustical keyboard instruments is that it is typically prohibitively expensive to provide a xe2x80x9cplayerxe2x80x9d version. Purchasers and owners of non-acoustical keyboard instruments sometimes desire, as do owners of pianos, that the keyboard instrument be able to play itself. Systems used to turn pianos into player pianos may be adapted for use with some non-acoustical keyboard instruments, but the cost and complexity is often high. For example, the player system may cost as much or more than the non-acoustical keyboard instrument, thereby doubling its purchase cost. Player systems typically provide both for operation of the keys and for sensing of key movement so that the playing of a musician may be xe2x80x9crecorded.xe2x80x9d One or both of these features is often desired by purchasers of non-acoustical instruments. In light of the above limitations of non-acoustical keyboard instruments, there is a need for improving the feel of these keyboards as well as for player systems designed for use with non-acoustical keyboard instruments.
There is disclosed herein a plurality of solutions to the shortcomings of the prior art. For example, according to one aspect of the present invention, a key actuation system is provided for a keyboard instrument. The keyboard instrument is of the type having a key fulcrum that pivotally supports a plurality of keys. Each key has a front end disposed forward of the fulcrum which is to be depressed by a player, and a rear portion which is disposed rearward of the fulcrum and that pivots upwardly when the front end is depressed. The key actuation system includes a pull solenoid which has a coil portion and a piston. The solenoid is operative when the coil portion is energized to draw the piston into the coil. The solenoid is mounted such that the coil portion is disposed above one of the keys and behind the key fulcrum. The piston is in mechanical communication with the rear portion of the key so that when the coil portion is energized and the piston is drawn into the coil, the rear portion of the key is lifted upwardly.